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Turbo high idle


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5 replies to this topic

#1 vagen

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Posted 06 January 2010 - 08:09 AM

I am experiencing a high idle with my turbo engine. When warmed up it rarely idles below 1500 rpm. Will a dirty iac cause this?

#2 eulogious

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Posted 06 January 2010 - 09:32 AM

We turbo owners don't really have an IAC, we have an AAV (Auxiliary Air Valve) that does the same thing. It's the thing located on top of the temp sensor, i believe.

I have been having weird idle issues as well, but really only in cold weather, until today actually, and I was thinking about posting about it, and then you beat me to it. So today I went out on my work break and sat in my car with it idling, and it wouldn't drop below 1500, even after 20 min of idling, so it was for sure warm. I turned it off, and then on about 3 times and the idle would start off at 900 to 1000 and then about 5 seconds later it would slowly climb to 1500 and stay there. I turned it off, went inside and came back out about 30 min later, started it and no idle problems. So ya. Same sorta issue. I am going to replace the AAV and see if that helps, I just need to get down to Turbones to pick it up, but time has just not been my friend lately.

The one thing that I am going to double check is to see if it's getting power to the AAV. I believe that the AAV is just a valve with a heat sensitive switch in it and a heating element. When you start the car, the heating element turns on and slowly heats up the switch causing it to slowly close, lowering the idle as it goes. Somebody correct me if I am wrong on this, that's just what it sounds like it does to me.

Other than checking for power and replacing it, I am stumped... I have asked how to clean it and didn't get a response, but cleaning it might help as well. I honestly haven't had too much time to look into it any farther than this...

#3 naru

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Posted 06 January 2010 - 10:21 AM

I am experiencing a high idle with my turbo engine. When warmed up it rarely idles below 1500 rpm. Will a dirty iac cause this?


Doubtful,but,clean it anyway.
Early turbos have an AAV,later ones an actual IAC.
Check the coolant temperature sender if you have the later style.

Both you guys should check for leaks in the rubber intake plumbing.
Move it around and listen for a RPM change.

Warm idle speed is adjustable BTW.

Edited by naru, 06 January 2010 - 10:33 AM.


#4 eulogious

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Posted 06 January 2010 - 10:59 AM

Warm idle speed is adjustable BTW.


Idles at 850 to 900 most of the time, so idle is fine, and I adjusted it when I got the car. I think the heating element went out on mine. Today before I left work I started my car and let it idle, and it was idling high (1500) again, so I let it warm up for a bit longer, and then drove it home. By the time I got home which was about 10 min later, it was idling fine (900). So my conclusion is that the heating element broke or I am not getting power to the AAV so therefore the engine is the only thing that is warming up the temp switch, so it just takes FOREVER to warm up completely. I am leaning towards the heating element is breaking/broke for me since the problem is intermittent at best. This is just a guess though and any other insight would be appreciated.

Early turbos have an AAV,later ones an actual IAC.


My turbo is a 1990 loyale wagon, so it's about as later as you can get, and I have the AAV, not the IAC. Also in my 88 FSM, it's referred to as the AAV on the turbo model, so I don't think this statement is true, but correct me if I am wrong.

Edited by eulogious, 06 January 2010 - 11:01 AM.


#5 naru

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Posted 06 January 2010 - 11:42 AM

You`re right.No IAC.Just a simple AAV.

Check it w/an ohmmeter if you are worried about the heating element.
Tap it lightly.

Hook a voltmeter to it to check for voltage supply interuptions.

Your time will be better spent looking at the hoses though,IMO.

#6 vagen

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Posted 07 January 2010 - 03:26 PM

the idle bypass screw was loose I mean really loose. I set the idle to 900 rpm with the engine hot and staked the screw. it should not fall out anymore.




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